Victor mathietj and felix dery



UNITED. STATES PATENT OFFICE.

VICTOR MATHIEU AND FELIX DERY, OF PARIS, FRANCE.-

SENSI TIZED PHOTOGRAPHIC PAPER AND PROCESS OF MAKING SAME.

SPECIFICATION forming part Of Letters Patent NO. 624,837, dated May 9, 1899.

Application filed January 31, 1899. Serial N0: 704,043. (No s ecimens.) I

have invented certaiunew and useful Improvements in Methods of Preparing Sensitized Paper for Polychromatic Photography; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has relation to the produc tion or manufacture of sensitized paper for chromatic photography; and it consists in amethod of producing or making this paper and imparting to it the properties indispensable to the uses made thereof.

- The sensitized paper used in polychromatic photography and the constitution of the prints reproducing all the colors in nature are of the class called carbon-papers and are sensitized and printed in substantially the same manner. However,in the printing of a monochromatic picture or image there is a certain elasticity or range in the exposure, and consequently in the tone of the print. This is not the case in printing from three films which by their superposition are to produce a polychromatic picture or image. The tones or tints must be produced in the same exact proportions in which they are found in the original, and in the practical reproduction of pictures requiring such exactitude a speciallyprepared paper becomes indispensablein order that all errors or inexactitude in printing may be avoided. The paper used by us does not difier from the so-called, carbon-papers, except in that the selected colors-yellow, blue, and red-are substituted for the carbon in the emulsion, which colors, by their combination, are to compose the polychromatic picture.

The process consists, essentially, in the'use of the provisional support itself for the mixture as a photometer in order to insure the rigorously exact reproduction. The colored tints being relatively clear ortransparent, it is possible to observe the image forming on the sensitized support as it darkens thereon,

which darkening takes place at the same time and proportionately to the action of the light upon the bichromated gelatin. It is therefore possible to follow the developmentof the image or picture and arrest its further development when of the required intensity. This being understood, we will describe the mode of preparing the paper. I

We first sensitize the paper with silver nitrate, then dry it, and coat it with a bichromated gelatin of the desired color in the usual manner.

Having thus described our invention, what We claim as new therein,and desire to secure by Letters Patent, is-' 1. The process-of making sensitized paper for polychromatic photography, which consists in sensitizing the paper with silver ni- Witnesses:

TRISTAN Gossn DE SERLAY, HENRI RACLOT. 

